1. Field of the Invention
The present invention relates to a cock for drawing-off carbonated liquid contained in a storage tank, which is maintained under pressure, for filling receptacles, such as bottles or the like. The invention will find application, particularly, in the drink industry with manufacturers and designers of machines used within the framework of this industry.
2. Description of Related Art
While drawing-off carbonated liquid from a tank, a number of precautions must be taken into consideration in order to guarantee the integrity and quality of the liquid, once the liquid has been distributed into individual receptacles. Specifically, during the filling operation, the carbonated liquid enters an important area of exchange with the surrounding environment. This surrounding environment, therefore, should be of an inert nature to avoid oxidation of the drink before consumption.
The drawing-off and storage of carbonated liquid is necessarily carried out under pressure. The pressure must be higher than the saturation pressure of the carbonated liquid, to avoid degasification of the liquid.
In view of the conditions set forth above, there has existed two prevailing methods of drawing-off carbonated liquids. The first consists of degassing the receptacle into which the liquid is to be drawn, and maintaining a pressure in the receptacle substantially equal to the pressure maintained in the storage tank of the drawing-off device. By means of a system of communicating vessels, the receptacle is then filled to the desired level. This is known as an isobaric drawing-off process.
During the isobaric drawing-off process, the receptacle is placed under pressure by a conduit extending inside the receptacle. After a pressure balance is reached, control means cause the opening of a drawing-off cock, allowing carbonated liquid to flow from the storage tank into the receptacle. During this filling process, gas contained in the bottle is either exhausted through a distinct channel or reinjected into the storage tank through a conduit having been used initially for placing the receptacle under pressure.
At the end of the filling process, the liquid contained in the bottle reaches the mouth of the gas exhaust conduit. This has a tendency to cause the pressure to rise in the receptacle, thereby stopping the flow of carbonated liquid into the receptacle. At that moment, a control means stops the flow of liquid, and the receptacle is again brought to atmospheric pressure before being withdrawn from the drawing-off cock and being directed towards a capping unit.
According to a second method, the pressure maintained at a vapor zone level of gas contained in the carbonated liquid storage tank is different from and higher than the pressure maintained in the receptacle. This is a phase-imbalance process. This process offers the advantage of reducing the filling time of a receptacle, but requires the use of level detection systems to detect the fill level in the receptacles. The principle of communicating vessels, as described above, is not available in this process.
Furthermore, these detection systems are presently considered to be unreliable and fairly expensive. This often leads carbonated drink manufacturers to use the principle of isobaric drawing-off.
The known drawing-off cocks of this type are usually comprised of a body having an external part capable of cooperating with the mouthpiece of the receptacle to be filled. Additionally, cocks of this type have an internal part located within the storage tank. This internal part comprises, more particularly, the control mechanisms to open or close the cock as well as means for placing the receptacle under pressure prior to the filling process. The external part of the body of the drawing-off cock comprises degassing means to bring the receptacle to atmospheric pressure at the end of the filling cycle and means for putting the receptacle under a vacuum or sweeping with a neutral gas at the beginning of the cycle.
As described above, the control mechanisms to open and close the cock as well as the means for placing the receptacle under pressure prior to filling, by bringing the receptacle's internal volume into contact with the gas contained in the storage tank, are housed inside the storage tank and, therefore, are immersed in the carbonated liquid.
These mechanisms are, in many cases, very complex and comprise, among other elements:
mechanical control means to open and close a valve;
flexible means for maintaining the valve in a closed position as long as the pressure balance in the tank and the receptacle has not equalized; and
a conduit obturating system ensuring communication of the internal volume of the receptacle with the gas contained in the storage tank.
The food industry is required to adhere to very strict standards of hygiene to ensure clean working environments. Therefore, the drawing-off cocks require frequent cleaning. The more the mechanisms are in contact with the carbonated liquid, the more difficult it becomes to clean the drawing-off cocks and to eliminate all residues capable of later contaminating the consumable product.
Although the system of communicating vessels to control and stop the filling process of the receptacles is most often used, there are, nevertheless, a number of disadvantages inherent in the process. The slightest change in pressure between the storage tank and the receptacle during the filling process modifies the rate of filling.
Furthermore, there is a known drawing-off cock apparatus for carbonated liquids under pressure, where all the control mechanisms, the flow control, and the means for placing a receptacle under pressure, are integrated into the cylindrical body of the drawing-off cock located around a coaxially arranged flow conduit. Although this particular design of the drawing-off cock limits the mechanical parts in contact with the carbonated liquid, there are a number of leak-proof connections required during a filling cycle, making this drawing-off cock unreliable. Further, the complexity of the control mechanisms also tends to adversely affect the reliability of this known apparatus.
Furthermore, in this known apparatus, a bellows diaphragm connects the upper part of the liquid flow-out conduit with the internal upper part of the cylindrical body where the feed-in of carbonated liquid occurs. Such a bellows diaphragm raises the problem of dismantling and cleaning an innermost recesses to maintain the aforementioned standards of hygiene in the food industry.
Moreover, this type of drawing-off cock uses a ball-valve located at the lower end of a flow-out conduit as a filling end detection and liquid flow-out stop control means. Experience has proven that such systems are not operationally practical because of their lack of reliability and accuracy.